Flexible expansion joints need to deal with bending and expansion of pipelines. Metal bellows expansion joints are well known conventional flexible expansion joints. Metal bellows expansion joints deform repeatedly to deal with the bending and expansion of pipelines and hence are liable to subject to metal fatigue. Considerably strong force needs to be applied to metal bellows expansion joints to deform the same and hence metal bellows expansion joints cannot be easily deformed.
A flexible expansion joint disclosed in, for example, JP 2008-180323 A for connecting pipes is capable of being fit over ends of the pipes respectively, without being specially worked and without requiring specially working the ends of the pipes.
FIGS. 1 to 3 show a pipeline including a pipe 1, a pipe 2, and a flexible expansion joint 100 connecting the pipes 1 and 2. The flexible expansion joint 100 has sleeves and sealing members.
FIG. 1 shows the flexible expansion joint 100 in a state where the pipes 1 and 2 connected by the flexible expansion joint 100 are coaxial and the axial distance between the respective ends of the pipes 1 and 2 is fixed.
FIG. 2 shows the flexible expansion joint 100 in a state where the axial distance between the respective ends of the pipes 1 and 2 connected by the flexible expansion joint 100 is not changed, the respective axes of the pipes 1 and 2 are separated from each other by a coaxiality deviation δ and the axis of the flexible expansion joint 100 is inclined at an angle θ1 to an axial direction. In the state shown in FIG. 2, the pipeline has an expansion allowance E.
FIG. 3 shows the flexible expansion joint 100 in a state where the axial distance between the respective ends of the pipes 1 and 2 connected by the flexible expansion joint 100 is changed, the respective axes of the pipes 1 and 2 are separated from each other by a coaxiality deviation δ, the axis of the flexible expansion joint 100 is inclined at an angle θ1 to the axial direction and the pipeline is elongate by an allowable axial length A.    Patent Document 1: JP2008-180323A